1. Field of the Invention
The present invention relates to an image display device, and more particularly to an image display device which includes a getter device, and to be more specific, the arrangement structure of a getter which is arranged in the inside of a getter device.
2. Description of the Related Art
As an image display device which performs a display by allowing electrons to impinge on a phosphor screen so as to make the phosphor screen emit lights, there has been known, for example, a field emission image display device which includes field emission electron sources, a thin film CRT (Thin Cathode Ray Tube) as represented by a surface-transmission-type image display device including surface-transmission-type electron sources, a cathode ray tube, or the like. This type of image display device is requested to hold a high degree of vacuum in the inside of a vessel so as to facilitate the movement of electrons.
In a conventional image display device, a getter is arranged on a plane coplanar with a plane of a back substrate on which electron sources are formed. When the getter is formed on the same plane as the electron sources, a display region part is formed with a small area or only a region where the getter is formed must be formed in an enlarged manner. Further, with respect to the evaporation-type getter, when the getter is arranged in the inside of an activated environment (a space in which electron sources are formed), electron emission portions of the electron sources are covered with a getter film thus reducing the electron emission ability.
Japanese Patent Laid-open 2003-528422 (patent document 1) discloses a means to cope with the above-mentioned drawback by forming a getter room in a state that the getter room is bonded to a display screen side of a display device. Further, Japanese Patent Laid-open Hei 9(1997)-129161 (patent document 2) discloses a means to cope with the above-mentioned drawback by forming a getter room in a state that the getter room is bonded to a back surface side of the display device.